Uphill vs. downhill cold start problem
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Uphill vs. downhill cold start problem
When I park the truck downhill it cold starts like a champ. When I park it uphill it doesn't. It will cough then act like it's starved for fuel for 15-20 seconds of cranking. Then it will start rough and smooth out after another couple of seconds.
It always starts fine when it's warm.
Has anyone heard of this?
To diagnose it further I'm going to switch to the other tank and park it uphill to see if it reacts the same. Maybe it's the in-tank fuel pump not getting the fuel up to the injector pump.
Dave
'94 F-350 Crew Cab
It always starts fine when it's warm.
Has anyone heard of this?
To diagnose it further I'm going to switch to the other tank and park it uphill to see if it reacts the same. Maybe it's the in-tank fuel pump not getting the fuel up to the injector pump.
Dave
'94 F-350 Crew Cab
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From: Saskatoon, Saskatchewan
You are experiencing a problem with the fuel filters. There is a fitting on the fuel filter which has a small orifice in it. If you park on an uphill it will bleed the fuel back to the tank and cause long cranking and poor running at first. Filling in the hole with some brazing will eliminate this problem. There is a Ford TSB out on this exact problem.
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From: Saskatoon, Saskatchewan
I would use brazing as the preffered material. It is the fitting on the side of the top of the filter housing that faces the engine. When you pull it off you will know you have the right one for sure. I am not sure where I read the TSB but I think it was on this sight.
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OK, I've looked at the filter and am not sure which fitting is the vent that allows the fuel to drain out of the line.
I'd appreciate any drawings or pictures describing how to fix the problem.
Thanks in advance.
I'd appreciate any drawings or pictures describing how to fix the problem.
Thanks in advance.
Posting Guru
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From: Monroe, WA
It's the small rubber line that comes off the top side of the filter base. It should be a 1/4 inch hose. Just for testing, pinch the hose with some small vise grips and give it a try. The others should be metal pipes. The real problem is most likely an air leak in your return lines and injector o-rings.
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Thanks. I'll give it a try. Wouldn't the leaks you suggest - o-rings, injectors cause a fuel leak? Why wouldn't those cause a problem when the truck is parked uphill and not downhill?
Thanks
Thanks
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Sometimes there can be an air leak that will allow air to suck in, but not allow fuel to run out. Also, as far as the problem with uphill/downhill, if you park facing downhill, the forces of gravity will keep fuel in the filters, etc. Park uphill and gravity pulls fuel away from them.
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I am having the same problem. So I clamped off the return line that runs to the outlet side of the fuel filter. So far so good, it has not starved today after many restarts.
To find this line look at your fuel filter, on my '84 6.9 it is mounted on a bracket at the front of the motor over the right side valve cover, on the front of the bracket is the steel line comming from the transfer pump. On the rear is the outlet side that runs to the injection pump. On the fitting on the rear of the bracket, is a rubber fuel line that runs to the fuel return system for the injectors. I clamped this line. It makes sense to clamp this line. If you have an air leak, when you start your engine the air is pushed into the fuel line that goes to the injection pump, causing the fuel starvation problem.
With this line clamped the air is pumped back to the fuel tank because the return system from the injectors joins up with the return from the injection pump at the back of the motor. This will not cure your air leak, only releve the fuel starvation problem.
I hope this helps. Me as well as others.
Happy Trails
Mike
To find this line look at your fuel filter, on my '84 6.9 it is mounted on a bracket at the front of the motor over the right side valve cover, on the front of the bracket is the steel line comming from the transfer pump. On the rear is the outlet side that runs to the injection pump. On the fitting on the rear of the bracket, is a rubber fuel line that runs to the fuel return system for the injectors. I clamped this line. It makes sense to clamp this line. If you have an air leak, when you start your engine the air is pushed into the fuel line that goes to the injection pump, causing the fuel starvation problem.
With this line clamped the air is pumped back to the fuel tank because the return system from the injectors joins up with the return from the injection pump at the back of the motor. This will not cure your air leak, only releve the fuel starvation problem.
I hope this helps. Me as well as others.
Happy Trails
Mike
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So, clamping the line fixes a problem w/ a leak somewhere else? Isn't that line a return so that the pump from the tank has a release so that it isn't pushing against a wall? If you clamp that line will the tank pump burn up or are there other adverse effects?
Thanks for any advice
-Dave
Thanks for any advice
-Dave
New User
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These old trucks, mine is an 84, dont have electric in the tank fuel pumps. Just a mechanical "transfer pump" and then the high pressure "injector pump". Clamping this line just keeps the return system from dumping air into the supply to the injection pump.
Mike
Mike
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Joined: May 2004
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From: Texas
This is odd. I was about to post the same problem here today. I am a total newbie to diesels and my 94 7.3L factory turbo 350 took a while to get started the past two days only after is sat overnight in my driveway pointed uphill. I will keep an eye on this thread and report any results from clamping or restricting holes.
This is an excellent forum, way over my head so far, but I like a good challenge!
This is an excellent forum, way over my head so far, but I like a good challenge!